The Desert Research Institute's 1999 Nevada Medal will be awarded to Dr. Wallace S. Broecker, a geochemist at Columbia University's Lamont-Doherty Earth Observatory, who has tied the global circulation of heat energy by ocean currents to the process of climate change. The minted, pure-silver Nevada Medal and $10,000 prize are underwritten by the shareholders of Nevada Bell.

Broecker will present the Nevada Medal Lecture "Surprises in the Greenhouse?" on March 23 at the University of Nevada, Reno, and on March 25 at the University of Nevada, Las Vegas. His talk will concern the influence of increasing greenhouse gases on the global "ocean heat conveyor," possibly resulting in abrupt shifts in climate.

"The climate system is an angry beast, and we are poking at it with sticks," says Broecker. His research indicates that ancient sediments and other geologic evidence point to brief, but dramatic "flickers" in global temperatures as the climate readjusts itself, prompting changes in the paths of the heat-bearing ocean currents.

Broecker has calculated that deep ocean currents, flowing with a volume of more than a hundred Amazon Rivers, provide the North Atlantic with an amount equivalent to one third of the heat energy it receives from the sun. He points out that if the ongoing increase in atmospheric CO2 levels were to trigger another such reorganization, "it would be bad news for a world striving to feed 11 to 16 billion people."

Broecker, who received the 1996 National Medal of Science, has a direct Nevada connection. He received his Ph.D. from Columbia, basing his thesis on the problems associated with determining the age of the formation of ancient Lake Lahontan's shorelines in Nevada.

As part of the Nevada Medal celebration, Broecker will be feted at award dinners in both Reno-March 23-and Las Vegas-March 25. For further information about the dinner events, contact Tonya Drake in Reno at (775)674-7555, or Christine Wilson in Las Vegas at (702)895-0523.

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